import java.util.Scanner;

public class Test11_15 {
    int recursion(int k, int n){
        int result;
        if(k==0 || k==n){
            return 1;
        }else{
            return recursion(k,n-1)+recursion(k-1,n-1);
        }
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Test11_15 test11_15 = new Test11_15();
        while (sc.hasNextInt()){
            System.out.println(test11_15.recursion(sc.nextInt(),sc.nextInt()));
        }
    }
}
